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Total Synthesis Of Surface Glycoantigen From Acinetobacter Baumannii Strain ATCC 17961

Posted on:2024-04-07Degree:MasterType:Thesis
Country:ChinaCandidate:L C DuanFull Text:PDF
GTID:2531307112969949Subject:Organic Chemistry
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Acinetobacter baumannii is a gram-negative bacterium,which is a common pathogen causing soft tissue and urinary tract infections,septicemia,pneumonia and meningitis,and ranked first in the List of Key Pathogens for New Antibiotic Research and Development released by the World Health Organization in 2017.Moreover,since COVID-19 emerged in 2019 and caused a continuous global pandemic,the risk of its infected hospitalized patients developing mechanical ventilator-associated pneumonia caused by A.baumannii has greatly increased.Carbohydrate-based vaccines are emerging immune vaccine,and immunization is an effective way to prevent and treat infectious diseases.In this paper,we have completed the synthesis of the surface glycoantigen from A.baumannii ATCC 17961,which can be used to develop a synthetic carbohydrate-based vaccine against A.baumannii infection.A.baumannii ATCC17961 lipopolysaccharide O-antigen consists of pentasaccharide repeating unit(with core trisaccharide repeating unit [→6)-β-D-Glc(1→3)-β-D-Gal NAc(1→3)-α-DGal(1→],β-linked to a 2,3-diacetamido-D-glucuronate at C4-OH of Gal and β-linked Glc NAc at C6-OH of Gal).The oligosaccharide molecules we synthesized include core trisaccharide 2-1,tetrasaccharide 2-2 and 2-3 with different branches,pentasaccharide2-4 with single repeating unit and decasaccharide 2-5 with two repeating units.We have completed the synthesis of trisaccharide and tetrasaccharide by selecting appropriate protective groups and flexibly adjusting the donors.We found when the C-2’ protecting group of the adjacent sugar in the disaccharide donor is levulinoyl group(which can cooperate with the C-2 acyl group for β-glycosylation reaction through hydrogen bonding),the stereoselectivity of glycosylation of the disaccharide donor and the highly branched galactose receptor can be significantly improved.Benefit from that,we have achieved the efficient synthesis of pentasaccharide donors and receptors by using[2+1+2] one-pot glycosylation method with single catalyst,which were further used in the synthesis of decasaccharide.
Keywords/Search Tags:Acinetobacter baumannii ATCC 17961, surface glycoantigen, Glycosylation, One-pot synthesis
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